The present invention is directed to the wooden barrel aging of alcoholic beverages such as distilled spirits, wine, and beer. During typical wooden barrel aging of distilled spirits derived from grains and other farm sources, from 2 to 50 wt % or more of the distilled ethanol and water in the mixture diffuses between and through the wooden barrel components (staves and heads) and thereafter evaporates into the surrounding atmosphere. The diffusion and evaporation continues throughout the aging period, which can be from a few weeks or months up to 20 years or more. The extent of evaporation depends on the initial alcohol content of the distillate, the duration of aging in the wooden barrels, relative humidity, ambient temperature, etc. The distilled spirits industry defines this loss as the “angels' share.”
The amount of water, ethanol, etc lost through evaporation when aging distilled spirits in 53 gallon white oak barrels over periods of time ranging from 1 to 20+ years ranges from about 2% per year to about 10% per year, depending upon the ambient conditions during aging, e.g., depending upon the climate. The distillate is considerably stronger upon emerging from the distillation process than it is after aging for 10 years, as ethanol loss is greater than water loss. The loss of ethanol during aging has adverse effects over and above the loss of the alcohol itself. The release of alcohol into the atmosphere around the barrels produces an explosion hazard, as the high ethanol content in the air can ignite explosively if subjected to spark or flame. Evaporated ethanol released into the ambient environment also serves as sustenance for black fungi and/or molds growing on warehouse walls, adjacent buildings, cars, etc.
For many decades, distillers have attempted to reduce the angels' share during aging of distilled spirits and wine in wooden casks. Barrels have been provided with coatings, including coating of the outer surface of barrel staves and/or barrel heads. Bonding agents have been used between the staves. Barrels have been made from reconstructed staves having intermediate plies of non-porous material. Barrels have been placed inside bags made from a multilayer film having an aluminum foil layer with vinyl on each side, with the atmosphere evacuated and the bag heat sealed closed. Wooden barrels have been suspended in a secondary container (e.g., metal barrel) over a reservoir of ethanol inside the metal barrel. Metal barrels containing distillate have been aged by suspending wooden staves in the distillate, with oxygen supplied to the system. Finely pulverized wood has been added to distillate in a container to accelerate aging of the distillate. Aging of distillates has also been accelerated by increasing the reaction of ethanol with the atmospheric oxygen. However, none of these solutions has proven to significantly reduce the Angels' Share while maintaining or improving the organoleptic properties of the alcoholic beverage. It would be desirable to find a way to age alcoholic beverage in a manner allowing the development of desirable organoleptic character while reducing loss due to angels' share diffusion and evaporation.